[PATCH] D141796: [15/15][Clang][RISCV][NFC] Set data member under Policy as constants

[Yueh-Ting (eop) Chen via Phabricator via cfe-commits]

eopXD created this revision.
eopXD added reviewers: craig.topper, kito-cheng, rogfer01, frasercrmck.
Herald added subscribers: VincentWu, vkmr, evandro, luismarques, apazos, sameer.abuasal, s.egerton, Jim, benna, psnobl, jocewei, PkmX, the_o, brucehoult, MartinMosbeck, edward-jones, zzheng, jrtc27, shiva0217, niosHD, sabuasal, simoncook, johnrusso, rbar, asb, arichardson.
Herald added a project: All.
eopXD requested review of this revision.
Herald added subscribers: cfe-commits, pcwang-thead, MaskRay.
Herald added a project: clang.

The object is now correct by construction.

This is the 15th commit of a patch-set that aims to change the default policy
for RVV intrinsics from TAMU to TAMA.

Please refer to the cover letter in the 1st commit (D141573 <https://reviews.llvm.org/D141573>) for an
overview.

Depends on D141793 <https://reviews.llvm.org/D141793>.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D141796

Files:
  clang/include/clang/Support/RISCVVIntrinsicUtils.h
  clang/lib/Support/RISCVVIntrinsicUtils.cpp


Index: clang/lib/Support/RISCVVIntrinsicUtils.cpp
===================================================================
--- clang/lib/Support/RISCVVIntrinsicUtils.cpp
+++ clang/lib/Support/RISCVVIntrinsicUtils.cpp
@@ -1011,7 +1011,6 @@
   };
 
   if (PolicyAttrs.isUnspecified()) {
-    PolicyAttrs.IsUnspecified = false;
     if (IsMasked) {
       Name += "_m";
       if (HasPolicy)
Index: clang/include/clang/Support/RISCVVIntrinsicUtils.h
===================================================================
--- clang/include/clang/Support/RISCVVIntrinsicUtils.h
+++ clang/include/clang/Support/RISCVVIntrinsicUtils.h
@@ -93,13 +93,15 @@
 };
 
 struct Policy {
-  bool IsUnspecified = false;
+  const bool IsUnspecified = false;
   enum PolicyType {
     Undisturbed,
     Agnostic,
   };
-  PolicyType TailPolicy = Agnostic;
-  PolicyType MaskPolicy = Agnostic;
+  // The default assumption for an RVV instruction is TAMA, as an undisturbed
+  // policy generally will affect the performance of an out-of-order core.
+  const PolicyType TailPolicy = Agnostic;
+  const PolicyType MaskPolicy = Agnostic;
   Policy() : IsUnspecified(true) {}
   Policy(PolicyType TailPolicy) : TailPolicy(TailPolicy) {}
   Policy(PolicyType TailPolicy, PolicyType MaskPolicy)
@@ -419,7 +421,6 @@
     return IntrinsicTypes;
   }
   Policy getPolicyAttrs() const {
-    assert(PolicyAttrs.IsUnspecified == false);
     return PolicyAttrs;
   }
   unsigned getPolicyAttrsBits() const {
@@ -430,8 +431,6 @@
     // constexpr unsigned RVV_VMA = 0x2;
     // int PolicyAttrs = 0;
 
-    assert(PolicyAttrs.IsUnspecified == false);
-
     if (PolicyAttrs.isTUMAPolicy())
       return 2;
     if (PolicyAttrs.isTAMAPolicy())


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